There are many applications where zones in a borehole need isolation from each other in an annular space between a tubular string and the borehole wall. The borehole wall can be the formation and is referred to as open hole or there can be one or more casing strings attached in series in the case of a cased hole. Apart from the structure and shape of the borehole wall there are a large number of designs for annular barriers that need to span the gap between a tubular string in the borehole and the borehole wall. There are also a broad range of operating conditions that dictate the use of some known designs as opposed to others. In some cases the controlling criteria is pressure differential or/and service temperature. In other cases the percent expansion from the run in to the set dimension for the sealing element is controlling. Some designs use an external sleeve on a mandrel and internally expand the mandrel for high pressure isolation where there may be high temperatures well over 400 F, as shown in US 2003/0042028. Many designs simply axially compress an annularly shaped sealing element and employ embedded stiff rings at the opposed ends to control seal element extrusion as in U.S. Pat. No. 6,102,117. Others specially design the slip assemblies to handle high pressure differentials such as barrel shaped slips shown in U.S. Pat. No. 5,944,102. Yet other designs push a sealing element up a ramp to axially compress it and to bring it to the surrounding borehole wall as in U.S. Pat. No. 8,109,340. Some high expansion designs are shown in U.S. Pat. Nos. 6,827,150 and 6,041,858. Another design provides an extrusion barrier for a sealing element in the form of a slotted ring as in U.S. Pat. No. 8,701,787.
As an alternative to these designs a high pressure and temperature annular barrier is presented with a host of unique features. While actuation starts with an axial force along a mandrel that force moves a plurality of rings closer together. In between the actuation rings are spring discs rotationally locked to a mandrel. The actuation rings have an exterior circumferential projection which catches a sloping segment of an adjacent spring disc to exert a pivoting motion on the sloping portion of the spring disc such that a curled outer segment that is registered with a depression in a surrounding corrugated member results in pushing a respective corrugation radially. Externally the corrugated member has a series of valleys spaced between peaks. Those skilled in the art will not that the internal valleys where curled segments engage also define the spaced external peaks. A sealing material is disposed in the external valleys between the external peaks. The tube shaped corrugated member is design to yield as the sealing material in its outer valleys is pushed to the borehole wall. Because the sloping segment of the spring discs essentially rotates about the outer surface of the mandrel, the exterior valleys of the corrugated member get axially squeezed as the external peaks approach the borehole wall. This effect pushes the sealing material in the external valleys of the corrugated member out toward the borehole wall for enhanced sealing contact. The external peaks of the corrugated member also serve to control seal material extrusion in the axial direction along the length of the seal material as opposed to prior designs that focused extrusion control at ends of sealing elements. The corrugated member can be formed with one or more continuous spirals so that the sealing elements in the external groove can be continuous. Alternatively, the corrugations can be an array of parallel peaks and valleys with each external valley having a discrete seal ring. Optionally a the corrugated member itself can be a sealing element by the manner in which it is built such as with an external resilient coating that can handle the operating temperatures as high as 600 F.
The spring disc can be used by itself or in a stack or an array of separated discs in other applications than a high pressure high temperature packer described herein. These discs with their finger structure and end reinforcing in the form of a loop can be supported on a mandrel alone or in stacks or arrays and when rotationally locked have finger structures extending radially to conform to a surrounding environment, which could be an open hole borehole wall, a cased hole or some intermediate barrier that interacts with an irregular surface such as the packer application described herein or an anchor. The flexible fingers allow for a smaller run in dimension where the sleeve can be retracted to release the fingers to the set position. Alternatively, the discs can be run in relaxed and then actuated with flexing about a rigid base ring to radially extend further for a support or a barrier function using direct or indirect contact with the surrounding borehole. The base ring can be rotationally locked to a common mandrel.
These and other features will be more readily appreciated from a review of the detailed description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.